wr450 yz cam change



In the middle of a yz450 cam change for my wr450, took the top cap off noticed at tdc the exhaust cam lined up and the inlet was way off few of the cam cap bolts were finger tight too, great ay. Anyway decided to take the inlet cam off at the same time to re align everything. i have hit a few problems. I have follwed a guide and read the manual but mine just doesnt seem to sit correctly i dont believe, after removing the chain tensioner theres obviously a little right and left play of the chain not loads. My cams look like this, they may be fine but im just not happy.

Any advice or help would be great


think i have just realised whhat i have done arrgghhhh i have allinged it and taken it off on the H marking, i thought it was a I not a long H am i pretty much knackerd now?

ok i have taken the cams out again turned the engine off to proper I tdc mark now the lobes and cams look like this.....



From here it looks like the exhaust cam is a tooth off.  Looks like you don't have the tensioner in.  If you put your finger in there and take the slack out of the chain the dots will move some.  That's what it looks like from the pictures in my opinion.  If it jumped a tooth while it was runnning or something that doesn't sound good.

no im installing a yz450 exhaust cam in my wr450 with my finger in there it seems to look better the dots match the top of engine, and the lobs look a little more even

Thats it now with cam chain tensioner in


Still looks a tooth off to me.  If you look at the other two dots, there's 13 pins between the dots with the WR cam.  I think there should be 14 pins with YZ cams.  Might want to get another opinion, I don't do this for a living or anything.


edit: I got that backwards, 14 pins on the WR and 13 on the YZ.  You shouldn't believe anything I say on the internet

Edited by chu

ok so theres 13 atm, think 14 may be the 426 i may be wrong probably am.

looking at it though if i go one lower on exhaust cam the dot will be way lower than the engine line hmmmm, thanks for your help

Yeah, I think I got that backwards about the pins.  Sorry about that.  You probably can tell if it's lined up in person better than I can from a picture because of angles and stuff.  Oh yeah, you can put something in the spark plug hole like a pencil or a socket extension and move the crank back and forth.  When it's at it's highest point you are at top dead center.

Edited by chu

cool ill try that thanks mate, so this is the lobe posistion at the tdc marking on crank with wr inlet cam and yz450 exhaust cam....


I'd say that looks more correct than in the first post where they're 14 pins apart.

The pics on your first posting show a misaligned cam (YZ cam with WR timing).

The pics in the subsequent postings show correct YZ timing of a YZ cam.


My WR450F'12 experience was:

- them side punch marks line up perfectly when the cams are installed right AND one sticks the finger into the cam tensioner's hole

- the top punch mark is manufactured always at a constant offest relative to the lobes for both YZ or WR cams

- the side mark of an cam to be sold as WR cam differs from a YZ cam (that is the only thing YAMAHA changed in '03-'05 with exhaust cams)

- hence the pin count between top mark and side mark of an exhaust cam varies, depending on YZ or WR cam

- hence WR timing: 14 pins between top marks,  YZ timing 13 pins between, but check first!


If you

- verify the 14 pins of WR timing and

- check the YZ cam you want to install for punch mark positions BEFORE messing up anything and

- tie the intake cam's sprocket to the chain,

then it is way easier to get the YZ timing right if one checks the 13 pins between top marks than verifies the alignment of both side marks.

Note: I never open the intake cam's bolts, I tie the chain to the cam, but I always remove the tesioner completely.


If you want to see them side marks aligned perfectly (highly recommended before closing the lid)

1 the RIGHT end of the crank's TDC mark must be under the TDC check hole's indicator

2 you have to simulate the tensioner by finger pressure

3 most importantly, you must look precisely at cylinder head seal level.



DO NEVER turn the crank around w/o cam tensioner in place or you WILL have to realign BOTH cams! BTDT

Edited by WRF-Rowdy

I'd say that looks more correct than in the first post where they're 14 pins apart.

Nope. First post has both side mark "under water" and visible slack in the chain. That's a YZ cam at WR timing.

Don't forget only grinding the decomp pin will restore e-startability.

But you can safely check out engine power band changes, just have to kick it to life.

ok great thanks so the very last picture in my posting looks correct? Wr450 with a yz exhaust cam i hopse so as im about to start it

just realised from looking at see level my wr inlet cam is just below and the yz exhaust cam is above

I don't think all the marks ever line up super precisely.  Maybe you're a degree or so before top dead center or there's a little wear in some bearings or the chain or something.

Edited by chu

just realised from looking at see level my wr inlet cam is just below and the yz exhaust cam is above

Basically ok 'cuz:    -X  +  +X = 0  (e.g. the cams relative position is ok)


Let's check if you are at TDC:


If the yz punch mark is above cylinder head level, 

remove the crank's TDC spy plug and - depending on wheter you took out the spark plug you'll need more or less force -

very gently knock onto the kickstart lever until the exhaust cam punch mark ist perfectly level.


Then you should see the right end of the TDC mark on the flywheel directly below the crank peek hole's center mark.

(At least that is where it was when my WR+YZ cam combo was lined up perfectly)

Get a torch, it's hard to see where the crank's mark is.


If you end up too far behind TDC then DO NOT TURN the crank a full turn w/o tensioner  installed!




I've to admit you should probably to it by the book, and remove the crank TDC peek plug AND the center crank turn-by-wrench plug.

That way yout can wiggle the cam fore and aft precisely using a socket, w/o the crude help of the kickstarter

and you won't come up with the urge to turn the crank around w/o cam chain tensioner in place.


I've to admit I like to do things with unscrewing only the minimum necessary amount of bolts.

One can do the cam swap with sparkplug, intake cam bolts and center crank plug in place,

the only thing that has to come off is the tensioner, and the TDC check plug.

Edited by WRF-Rowdy

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